The purpose of the proposed research is to reveal principles of nervous system function in the control of basic behavior patterns such as feeding and mating. We are finding that hypothalamic reward and punishment mechanisms serve a homeostatic function by translating physiological imbalances into corrective behavioral action. Electrical stimulation of certain brain regions can be rewarding as evidenced by self-stimulation behavior, or it can cause aversion shown by responses to escape from stimulation. Our research is demonstrating that lateral hypothalamic self-stimulation and stimulation-escape are controlled by the same oral, postingestional and weight related factors which control feeding. The factors which augment food intake increase the reward of self-stimulation and decrease escape; conversely, satiety factors cause a shift from reward to aversion. It therefore appears that hypothalamic reward is involved in rewarding eating when the animal is hungry, and hypothalamic aversion is involved in punishing eating when the animal is satiated. Similarly for mating, we find hypothalamic sites where self-stimulation decreases after castration, with reversal by androgen therapy; whereas stimulation-escape increases after ejaculation. Apparently this is a reward-aversion system controlling mating. The proposed research program has grown out of this work. For the next five years we plan eight intertwined lines of research including studies of the following: Glucostatic and hormonal controls of self- stimulation and stimulation-escape; the role of the ventral noradrenergic bundle in inhibition of feeding and self-stimulation and in anorectic drug action as indicated by our studies showing hyperphagia after norepinephrine depletion with 6-hydroxydopamine; similar studies after seratonin depletion; further tests of the mating-reward-aversion hypothesis; new tests to find brain reward and aversion related to mouse-killing, and tests of rats with all three types of electrodes to determine the conditions of specificity for self-stimulation related to feeding, mating and aggression.